Herbicides

ABSTRACT

HERBICIDAL COMPOSITIONS CONTAINING O-(NITRO-4-ALKYLPHENYL) - O - ALKYL - N - ISOPROPYL-AMIDO-PHOSPHOROTHIOATES, AND HERBICIDAL USES THEREOF.

United States Patent Int. Cl. Aoln 9/20 US. Cl. 71-87 7 Claims ABSTRACT OF THE DISCLOSURE Herbicidal compositions containing 0-(2-nitro-4-alkylphenyl) 0 alkyl N isopropyl-amido-phosphorothioates, and herbicidal uses thereof.

This application is a division of applicants Ser. No. 874,954, filed Nov. 7, 1969 now U.S. Pat. No. 3,636,143.

The present invention relates to certain new amidothionophosphoric acid esters, to a process for their production and to their use as herbicides.

The compounds of the present invention are O-(Z-nitro- 4 alkylphenyl) O alkyl N-isopropylphosphoroamidothioates, of the following general formula: 1

l-CaH1NH (1) wherein R and R' are each an alkyl radical having 1-4 carbon atoms.

It is already known that amidothionophosphoric acid esters of the following general formula possess insecticidal and activities (British Patent Specification 'No.

have any herbicidal activity. There is also no mention of any applicability to soil or any indication that one might expect them to have herbicidal activity.

Compounds of US. Pat. No. 3,074,790, for example 0- (2,4-dichlorophenyl) O methyl N-isopropylphosphoroamidothioate, have herbicidal properties, and the present inventors have investigated the herbicidal activity of various derivatives of these amidothionophosphoric acid esters and have discovered that the compound of the following structure has particularly excellent herbicidal efficacy (Japanese Patent Application No. 78,104/66):

i-CsHrNH (3) It was most surprising to find that the compounds of formula (1), which may be considered as derivatives of the compound of formula (3) substituted by an alkyl radical, in the para-position, are excellent herbicides. Especially when a pre-ernergence applicaton is made, they show remarkably excellent effect in killing weeds and yet they do not appear to have any phytotoxicity to cultivated plants.

It is preferred that R' be a methyl radical. Preferred compounds therefore have the formula:

As mentioned above, the present invention is based on the discovery that the compounds of formula 1) show remarkably excellent herbicidal efficacy when used as herbicide and especially when applied to soil before germination. This is particularly surprising, since they are inferior to the known compounds having analogous structure in insecticidal and fungicidal properties.

The invention also provides herbicidal compositions containing the amidothionophosphoric acid esters of general formula (1) as active ingredient in admixture with a solid diluent or carrier or in admixture with a liquid diluent or carrier or in admixture with a liquid diluent or carrier containing a surface active agent. The invention also provides a method of combating weeds which comprises applying to the weeds or a weed habitat an amidothionophosphoric acid ester of the formula (1) alone or in admixture with a solid or liquid diluent or carrier, especally to soil before germination.

The compounds of the present invention are distinguished by their lack of phytotoxicity to rice plants and by the small amounts (compared with pentachlorophenol (PCP) and 2,4 dichlorophenyL- 4' nitrophenyl ether (NIP) etc.) are needed to give good results in paddy fields. A similar effect to that of SIMAZIN may be expected without harm to cultivated plants when the active compound is applied to soil before germination for the purpose of controlling weeds in upland fields. Especially when applied to soil before germination, the active compounds of the invention are better than certain previous herbicides in that they show a superior selective herbicidal activity depending on the amount applied.

Table I contains examples of the compounds to be used in this invention.

TABLE I Structural formula Chemical name NO: (5) O-(2-nitro-4-methylphenyl) O-methyl N-isoprol- CH;0 S pylphosphoroamidothioate.

o-@433, i-CIH'IN N0; (6) 0-(2-nitro-4-methylphenyl) O-ethyl N-isopropyl- C:H O S phosphoroamldothioate.

i -OQ-Cm i-CaHrN N0; (7) O-(2-nltro-4-methylphenyl) O-n-propyl N-isopron-C H O S pylphosphoroamidothloate.

i 0CH| i-CgHIN NO; (8) O-(Z-nitro-S-methylphenyl) O-lsopropyl N-lsopro- 1C;H10 S pylphosphoroamidothloate.

i -QG-om l-omm N01 (9) 0-(2-nltro-4-methylphenyl) O-n-butyl N-lsopropyln-C H 0 S phosphoroamidothioate.

fl e-4311. -C;H1N

N01 (10) O-(2-nltro4-methylphenyl) 0-lsobuthyl N-isoprol-CJLO B pylphosphoroamidothtoate.

-O--CH, i-CJLNQ C1H50\E /GH; (11) o-g-lngltlmzgggg gatlgggg. O-ethyl N-lsopro- 1C;H1N CH;

The invention provides a process for the production of a compound of the formula (1) in which (a) An 0 alkyl N isopropylamidothionophosphoric acid ester halide of the formula:

RO\fi P-Hal l-C;H1N (1 is reacted with a 2-nitro-4-alkylphenol of the formula:

III 02 (13), and the product is reacted with an alkali metal alcoholate of the formula:

M'O-R in which M is an alkali metal; or

(c) A N isopropylamidothionophosphoiric acid dihalide of the formula (14) is reacted with an alkali metal alcoholate of the formula (15), and the product is reacted with a 2-nitro-4-alkylphenol of the formula 13) either in the form of a salt or in the presence of an acid-binding agent.

/LHal MO R s l- C gHzNH RO\S wQ-R M1181 lemma 6) This process is preferably carried out using an inert organic solvent (this term includes a mere diluent). Examples of suitable solvents include aliphatic or aromatic hydrocarbons (which may be halogenated), for example benzine, methylene chloride, chloroform, carbon tetrachloride, benzene, chlorobenzene, toluene, xylene; ethers, for example dietheyl eher, dibutyl ether, dioxan, tetrahydrofuran; and aliphatic alcohols or ketones which have low boiling points, for example methanol, ethanol, isopropanol, acetone, methylethyl ketone, methyl isopropyl ketone, methyl isobutyl ketone. Lower aliphatic nitriles, for example acetonitrile, propionitrile, may also be usable.

As already mentioned above, variant (a) may be carried out in the presence of acid-binding agents. For this purpose, alkali metal carbonates, bicarbonates or alcoholates, such as potassium carbonate, sodium bicarbonate, sodium carbonate, or sodium or potassium methylate 0r ethylate, or aliphatic, aromatic or heterocyclic tertiary bases such as triethylamine, diethylaniline, pyridine, etc. may be used. Instead of reacting in the presence of an acid-binding agent, a salt of the corresponding 2-nitro-4- alkylphenol, preferably an alkali metal or ammonium salt, may be provided and then reacted salt with the O-alkyl N-iso-propyl-amidothionophosphoric acid ester halide. The reaction may be carried out within a fairly wide temperature range, but in general at temperatures of 30 C. to C., preferably 40 C. to 70 C.

In variant (b), one may for example proceeed as follows. In one of the inert solvents mentioned above, preferably alcohol, 1 mol of alkali metal or ammonium salt of 2 nitro 4 alkylphenol is dissolved and the solution is added dropwise to 1 mol of N-isopropylamidothionophosphoric acid dihalide and the mixture is heated at 45 70 C. for a short time. Then the mixture is cooled to room temperature and mixed with 1 mol of alcoholic solution of alkali metal alcoholate. For completing the reaction, the reaction mixture is again heated at 40-70 C. for a short time and the excess of alcohol is distilled off under reduced pressure. The residue is dissolved in a water-immiscible solvent, preferably one of the aforementioned hydrocarbons or ethers, and the solution is washed with water. Further, after washing with a solution of diluted alkali metal hydroxide or ammonium hydroxide, the organic phase is dried and the solvent is removed by distillation; the final compound is obtained as the residue.

Variant (b) is illustrated by the following reaction schemes:

In variant (c) the starting materials are used in a different sequence. N-isopropylamidothionophosphonic acid dihalide is reacted firstly with alkali metal alcoholate solution and then the intermediate product formed is reacted with 2 nitro 4 alkylphenol. When applying this variant of the process, the conditions of the reaction may be the same as those mentioned above.

Variant (c) is illustrated by the following reaction schemes:

ROS

The process for the preparation of a compound according to the invention is illustrated by the following Example 1.

Example I i-C H NH 76 g. (0.5 mol.) of 2 nitro 4 methylphenol were dissolved in 400 ml. of acetonitrile and 8.0 g. of dried and sifted potassium carbonate (K 00 were added to the solution. During vigorous stirring, 102 g. (0.5 mol.) of

short time, and the solvent was removed completely. In

this way, 127 g. of O-(2-nitro-4-methylphenyl)-O-ethyl N ethyl N isopropylphosphoroamidothioate were obtained. If the same operation is carried out using 2-nitro- 4 ethylphenol or 2 nitro 4 isopropylphenol in place of 2 nitro 4 methylphenol, O (2 nitro 4 ethyl- (or iso-propyl)-phenyl) O-ethyl N iso propylphosphoroamidothioate which has the same herbicidal activity is obtained.

-It has already been mentioned that the compound of the present invention is distinguished by superior heribicidal properties in comparison with previously known compounds synthesized in an analogous manner and to be used for the same purpose. This outstanding activity is apparently caused by the increase of the general herbicidal potency produced through the introduction of an alkyl radical to give the specific chemical structure.

When applied in larger quantities (5-40 kg. active ingredient per hectare), the composition according to the present invention shows non-selective activity and when used in lower concentrations (152 5-5 kg. per hectare), it shows selective herbicidal activity. For this reason, amido thionophosphoric acid ester of the present invention can be used as germination inhibiting agent, especially as weed controlling agent. The term weeds is used in the widest sense to mean all plants that grow where they are not wanted.

The compounds of the present invention show herbicidal activity in the case of, for example, the following plants. They show excellent selective herbicidal effieacy whenused in a suitable quantity (for example 11.25-5 kg. per hectare) as mentioned above and especially they can be used as herbicides in upland or paddy field-s where the marked plants in the list below are cultivated.

Dicotyledonous Weeds:

catch weed (Galium) chick weed (Stellaria) camomile- (Matricaria) French weed (Galinsog-a) goose-foot (Chenopodium) stinging nettle (Urtica) groundsel *(Senecio) wild amaranth Amaranthus) common purslane (Portulaca) Monocotyledonous Weeds:

timothy grass (Phleum) meadow grass (Poe) fescue grass Festuca) finger grass -(Digitaria) goose-grass (Eleusine) green lfoxtail (Setaria) ray grass (Lolium) barnyard grass (Echinochloa) brorne grass (Bromus) Dicotyledonous Crops*:

mustard -(Sinapsis) cress (Lepidium) cotton '(Gossypium) sugar beets '(Beta) carrots =(Daucus) 'beans (Phaseolus) potatoes (Solanum) coffee (Coffea) cabbage (Brassica) spinach (Spinacia) Monocotyledonous Crops*:

maize (Zea) rice (Oryza) oats (Avena) barley ('Hordeum) wheat (Triticum) millet (Panicum) sugar cane (Saccharum) The plant species given in the above enumeration are to be understood as representative examples of the genus designated in Latin. The applicability of 'the active compounds of the present invention is not limited to these genera, and they may be applied to other plants in the same way.

When the compounds of the present invention are used as herbicides, they may be applied directly diluted with water or in admixture with carriers and formulated into liquids, wettable powders, emulsifiable concentrates, dusts, granules, tablets, pastes, etc. by methods generally employed with the ordinary agricultural chemicals. Examples of solid carriers include inactive mineral materials such as talc, clay, kaolin, montmorillonite, diatomaceous earth, calcium carbonate, etc. Examples of liquid carriers are either solvents or even nonsolvents which can disperse or dissolve the chemicals by means of adjuvants, for example alcohols, benzene, xylene, dimethyl naphthalene, aromatic naphthas, dimethyl formamide, surface active agents, etc.

The efiicacy of the active compounds may be assisted by applying them in admixture with such adjuvants used for agricultural chemicals in general as spreaders, emulsifiers, wetting agents, adhesive agents, etc. Further, they can be applied in admixture with other herbicides such as phenoxy compounds, chlorophenol compounds, carbamates, diphenyl ethers or triazine compounds, and also with plant growth regulators, nematocides, soil disinfectants and other agricultural chemicals and fertilizers.

The present invention is further illustrated by the following working examples.

WORKING EXAMPLE 1 of the compound of formula (6) and 95% of a mixture of talc and clay are formulated into a dust by mixing and crushing, and the dust is used by dusting as it is.

WORKING EXAMPLE 2 20% of the compound of formula .(6), 75% of a mixture of Zeeklite and clay, 3% of sodium alkylbenzene sulphonic acid and 2% of sodium dinaphthylmethane disulphonic acid are formulated into a wettable powder by mixing and crushing, and the powder is applied diluted with water.

WORKING EXAMPLE 3 20% of the compound of formula (5), 75% of xylol and 5% of Sorpol (trade name of the product of Toho Kagaku Kogyo K.K., Japan) are formulated into an emulsifiable concentrate by mixing and stirring, and are applied diluted with water.

WORK'ING EXAMPLE 4 The compound of formula (8) is dissolved in xylol. The solution is sprayed onto clay granules while rotating and mixing so that about 10% of active ingredient can be incorporated. The granular formulation is used as it is by scattering on the surface of soil.

The compositions of the present invention generally contain 0.1-95% by weight, preferably (LS-90% by weight, of active compound.

The application of may be carried out by ordinary methods, for example watering, spraying, atomizing, dusting or scattering. The most suitable application time is before the germination of weeds to be eradicated. Especially when application is carried out mainly before the germination of cultivated plants, the general conditions, of cultivation are not so important, but the quantity of active compound to be applied per unit area and the application method are important.

The quantities of the active compound to be used acording to this invention may vary within a fairly wide range. They depend upon various factors, for example the condition of cultivation, soil, weeds and weather as well as the purpose of application in each case.

The outstanding herbicidal action of compounds of the present invention as well as their superiority as herbicides compared with previously known compounds is clearly shown by the following test Examples.

TEST EXAIWPL'E A Test against weeds of paddy fields Valuation Herbicidal eificacy: Phytotoxicity:

5 Highest efficacy 5 Highest phytotoxicity 4 Big eflicacy 4 Big phytotoxicity 3 Medium efiicacy 3 Medium-big phytotoxicity 2 Small efiicacy 2 Medium phytotoxicity 1 Slight efficacy 1 Small phytotoxicity 0 No eflicacy 0 No phytotoxicity The results are given in Table II.

TABLE IL-TEST RESULTS OF HERBICIDAL EFFICACY AGAINST WEEDS OF PADDY FIELDS AND PHY- TOTOXICITY TO RICE Herbicidal effect Barn- Broadyard Spike leaved grass rush weeds Quantity Compound of a.i. of formula to 6) (v)- 8) Phytotoxicity rice omcnvw lhth finhblmammmcnmmbiflv to 5}) suaooeneilsimml it OOHOOQOOOOOOOOOOOOOQOOOO NOTE: Broad-leaved weeds are Monochorla, Rotala indica Koehne False plmpernel, Gratiolajapontca Miquel, ete.; PCP=pentachlorophenoi (commerc al product); NIP=2,4'dichlorophenyl-4'-nitrophenyl ether (commercial product).

TEST EXAMPLE B Test against weeds of upland fields Test method: After filling up pots of 30 x 30 cm. were filled with soil of diluvial volcanic ash and in the pots were sown seeds of the weeds, upland rice (Hataminori variety) and vegetables mentioned in-Table III. After covering the soil, the compounds of the present invention, formulated as emulsifiable concentrates or wettable powders were sprayed on the surface of the soil in amounts of 400, 200 and g. of active ingredient per 10 a. After 9 10 3 weeks, herbicidal elfectiveness against the various weeds Seeds of test plants are sown on ordinary soil and after and phytotoxicity to the upland rice and various vege- 24 hours the preparation of active compound is sprayed.

tables were investigated. After 3 weeks, the degree of damage given to the test plants is observed and valued from to 5, as follows:

Slight damage or slight growth delay Markecli damage or growth delay Remarkable damage or only 50% germinated Plants are partially destroyed after germination or only 25% germinated 1 Plants died completely or no germination.

The results are given in Table IV.

Valuation Herbicidal eflicacy: Phytotoxicity:

Highest efiicacy Highest phytotoxicity Big efiicacy Big phytotoxicity Medium efficacy Medium-big phytotoxicity Small efficacy Medium phytotoxicity l0 Slightest efiicacy Small phytotoxicity No eificacy No phytotoxicity The results are given in Table 111. (CAT is 2-chloro- 4,6-bis (ethylamine)-l,3,5-triazine.)

TABLE III.-TEST RESULTS OF HERBICIDAL EFFICACY AGAINST WEEDS 0F UPLAND FIELDS AND PYHTOTOXICITY TO VARIOUS CROPS Herbicidai effleac Ph Q y y ytotoxelty of com- Barn- Wild 4 pound, yard Finger Dent ama- Common Upland Japanese Cucum- Compound of formula g./ a. grass grass (oxtail ranth purslaue riee radish ber Tomato Carrots 400 5 5 5 5 5 o o o o 0 200 5 5 5 5 5 0 o o o o 0 0 0 0 "i 200 5 5 5 5 5 o o o o o 100 5 5 5 5 5 0 0 0 o 0 (7 400 5 5 5 5 5 1 1 o o o 200 4-5 4-5 4 5 5 o o o o 0 l 100 4 3-4 3-4 5 4 o o o o 0 (8) 400 5 5 5 5 5 o 0 o 0 0 200 4-5 5 5 5 5 o o o 0 0 100 4 4 3-4 5 5 0 0 o o 0 (9) 400 4-5 4-5 4 5 5 I 0 o o o 0 200 3-4 5-4 a 3-4 4 0 0 0 o 0 l 100 2 2 2 a a 0 o 0 o o 400 4-5 4-5 4 5 5 0 o o o 0 200 4 8-4 3-4 4 4 o o o o 0 100 3 3 3 3 3 0 0 0 0 0 100 5 5 5 5 5 2 3 2 2 2 4 4 5 5 5 0 1 1 1 1 400 5 5 5 5 5 a 1 5 5 5 (C0mparlson) 200 5 5 4 5 5 0 0 2 2 3 No treatment 0 0 0 0 0 0 0 0 0 0 TEST EXAMPLE C Test on pre emergence SO11 treatment agamst The test results given in Table IV show that the com various plants pounds of the present invention can have excellent selec- T d M f d tive herbicidal eflicacy without causing any phytotoxicity 1 g f g ig g g i gz ggg yg g 33 523333 to cultivated crops when used in a suitable quantity (1.25 parts by weight of solvent (acetone) and 1 part by weight acme mgredlem Per Pectarey Especlauy of emulsifier (benzyloxypolyglycol ether), and h h herbicidal eflicacy is shown against barnyard grass (Echiemulsifiable concentrate is diluted with water to the de- 110611103), finger B (DlgltarlaL Common p sired concentration. tulaca), etc.

TABLE IV.TEST 0N PRE-EMERGENCE SOIL TREATMENT AGAINST VARIOUS PLANTS (POT TEST) Quantity Herbicidal eflicacy Phytotoxieity 0 com-- pound, Echi- Portu- Cheno- Stel- Amaran- Digi- Compound g./l0 a. noohloa iaca podium laria thus taria Wheat Barley Rice Cotton Maize Cabbage 2O 59 5 5 5 4 5 2-3 2-3 3 2 3 2-3 10 5 4 5 5 3 5 1 1 1 1 2 1 A.. 5 5 2 5 3 1 5 0 0 0 0 0 0 2. 5 4-5 0 3-4 1 0 4-5 0 (l 0 0 0 0 1.25 3 0 3 0 0 3 0 0 0 0 0 0 20 5 5 5 5 5 5 4 4 5 4 3 4-5 10 5 5 5 5 5 5 1-2' 2 3 2 3 2 B. 5 5 5 5 5 4-5 5 0 0 0 0 0 0 2. 5 5 4-5 4-5 4-5 3 4-5 0 0 0 0 0 0 1. 25 5 2 2 2 1 3 0 0 0 0 0 0 20 5 5 5 5 5 5 5 5 5 5 5 0 10 5 5 5 5 5 5 1-2 2 1-2 2 2 0 C 5 5 5 5 5 5 5 0 0 0 0 0 5 2. 5 5 5 5 5 5 5 0 0 0 0 0 2 1. 25 5 4-5 4-5 4-5 4 5 0 0 0 0 0 0 See the following 01 N 05 N0: CHgO s CH|0 S CQHBO 3 l l l 0- Cl -0 O -CH; (6) t-C flm l-CaH'lNfi t-C :HvN

Cgxaraogad known from U.S. Pat. No; Compound fol-comparison Componndotthepresentinvention gredient an effective amount of a compound of thefor.-

wherein R and R' are each an alkyl' radical having 14 carbon atoms in admixture with'a solid diluent or earlier or in admixture with a liquid diluent. or carrier containing a surface-active agent.

2. A composition according to claim 1 containing from 0.1 to 95% of the active compound, by weight.

3. A method of combating weeds which comprises applying to the weeds or a weed habitat a composition according to claim 1.

4; A method according to claim 3 in which the active compound ,is applied before germination of the weeds.

5. A method according to claim 3 in which the active compound is applied to an area of rice cultivation.

6. A method according to claim 3 in which the active compound is applied to an area of cultivation infested with weeds to combat the weeds without substantial injury to the crop.

7. A method according to claim 3 in which the active compound is applied in an amount of 1.25 to 5 kg. per hectare.

References Cited UNITED STATES PATENTS 3,472,920 10/1969 Schrader et al. 7l87 LEWIS GO'I'TS, Primary Examiner C. L. MILLS, Assistant Examiner 

